Blue phase liquid crystal (Liquid crystalline Blue Phases, BPs) is a special phase which is macroscopically between an isotropic liquid crystal and a cholesteric phase liquid crystal, and commonly occurs in a highly chiral liquid crystal system. Microscopically, the blue phase is of lattice defect without birefringence phenomena, of which the lattice size is comparable to the order of magnitude of the wavelength of visible light (hundreds of nanometers). Blue phases can be divided into three subphases according to the crystal structure, which are designated as Blue phase I (BPI), Blue phase II (BPII), and Blue phase III (BPIII), with the corresponding lattice structures of body-centered cubic, simple cubic, and amorphous state.
The blue phase liquid crystals have an electric field response time in microseconds due to the occurrence of Kerr effect, as compared to electro-optical response of the conventional liquid crystals. Moreover, the blue phase liquid crystal display has a wide visual angle, requires no liquid crystal alignment layer, has a low drive voltage (only ⅓ of that of TFT liquid crystal display), and it is therefore considered as the most promising rapid electro-optical response liquid crystal display material of the next generation.
Because a nano-liquid crystal complex has a very small Kerr constant, the working voltage of the liquid crystal display based on Kerr effect is still too high (>50 Vrms, wherein rms indicates root mean square, and Vrms indicates effective value of alternate current voltage), and thus such liquid crystal display cannot be effectively applied to conventional non-crystal thin film transistor.
The Kerr constant K is positively proportional to the following equation:
            Δ      ⁢                          ⁢              n        induced                    λ      ⁢                          ⁢              E        2              ≈      Δ    ⁢                  ⁢          n      ·      Δɛ        ⁢                            ɛ          0                ⁢                  P          2                                      κλ          ⁡                      (                          2              ⁢              π                        )                          2            
In the equation above, Δninduced indicates electric field-induced birefringence, λ is the wavelength of the incident light, E is applied electric field, Δn is the birefringence of the liquid crystal, Δ∈ is the anisotropic dielectric constant, k is the elastic constant, P is the screw pitch of the liquid crystal, and π is the circumference ratio.
As can be seen, increasing both birefringence and dielectric constant favors the increase of the K value. Therefore, it becomes a key to synthesize a liquid crystal material with a large dielectric constant and a large birefringence in order to increase the Kerr constant of blue phase liquid crystals. The present disclosure is directed to solving the problems of low Kerr constant of the blue phase liquid crystal composite materials produced using the methods known by persons skilled in the art and to providing a blue phase liquid crystal composite material with a large Kerr constant.